The objectives of this project are to determine how 2450 MHz microwave radiation interacts with biological material at the cellular and subcellular level, to observe any effects of this interaction, and to relate the amount of microwave energy absorbed to the effect. The biological specimens include macrophages, cardiac cells, lysosomes, and cellular enzymes. For these experiments, a wave-guide exposure apparatus has been developed which can maintain the specimens at physiologic temperatures (37 degrees C plus or minus 25 degrees C) at specific absorption rates up to 100 mW/g. No effects were noted on in vitro activity of (creatine phosphokinase and acetylcholinesterase) at SAR's up to 50 mW/g. Embryonic cardiac cells obtained from 9-day old quail, exhibited an increase in cell membrane permeability to typan blue at SAR's of 10, 50 and 100 mW/g. Lysosome fragility was not influenced by microwaves at SAR's up to 100 mW/g and exposure durations of 90 min. Other aspects of cell and organelles are currently being studied.